1. Field of the Invention
The present invention relates to a process for producing cold-rolled strips and sheets of austenitic stainless steel, which comprises cold-rolling a cast strip having a thickness close to the thickness of a product, which is cast by the synchronous continuous casting process in which there is no difference in the relative speed of the cast strip and the inner wall surface of a casting mold.
2. Description of the Related Art
According to the conventional process for producing cold-rolled strips and sheets of a stainless steel by the continuous casting method, a cast slab having a thickness 100 mm or more is formed by casting, while oscillating a casting mold in the casting direction, the obtained cast slab is surface-finished and is heated at a temperature 1000.degree. C. or higher in a heating furnace, the heated slab is hot-rolled to a hot strip having a thickness of several millimeters by a hot strip mill comprising rough-rolling stands and finish-rolling stand, the hot strip is annealed or not annealed, and the strip is descaled, cold-rolled, and subjected to final annealing.
The conventional process has problems in that large and long hot strip mills are required to hot-roll a cast slab having a thickness of 100 mm or more, and that large quantity of heat is necessary for heating and rolling the cast slab.
As the means for overcoming these problems, a process for producing a cast strip having a thickness equivalent or close to the thickness of the hot strip has been studied. For example, there can be mentioned a synchronous continuous casting process where there is no difference in the relative speed of the cast strip and the inner wall surface of a casting mold, such as a twin-roll method and a twin-belt method, as introduced in these specially published in "Iron and Steel", '85-A197 to '85-A256.
In the production of cold-rolled stainless steel strips and sheets through this synchronous continuous casting process, however, problems remain to be solved. Namely, where cold-rolled stainless steel strip is produced through this continuous casting process, since the processes from casting to final product are shortened, problems arise with respect to the surface state of the product.